Apple iOS 13.5 is the most important iOS update in years and my upgrade guide strongly recommends you install it. But it is not bug free.
Alongside growing reports of high battery drain, Apple customer support has confirmed to users that iPadOS can cause boot loops on the iPad Pro and media playback of the hugely popular MP4/MPEG-4 container format is broken for both iPad and iPhone owners.
Breaking down the former, AppleInsider states that the 10.5-inch iPad Pro is most commonly affected with reboots occurring “between 30 seconds and 45 seconds after logging in”. Full factory resets and even putting devices into DFU mode have not fixed the problem for many. Interestingly, there are also isolated reports of this impacting iPhones, while the issue seems to span both iPadOS / iOS 13.4.1 and 13.5 for impacted users.
It is a similar story with MP4 playback with the problem spanning both 13.4.1 and 13.5 and impacted users have lost access to their video libraries (1,2,3,4,5 etc) with native apps and third party apps like NPlayer and InFuse. While Apple switched default video recording to HEVC in iOS 11, support for this remains mixed so switching it to MP4 (still the most popular container format in the world) is a popular option.